SURVEY OF MUNICH TERTIARY BASIN 87 
southeastward along the 650-gamma isogam, and along a parallel 
slightly farther northeast and partly along the 675-gamma isogam 
and partly along the 700-gamma isogam. This latter zone of steeper 
than normal magnetic gradient suggests the presence of a structural 
(subsurface) fault scarp forming the west-southwestern edge of the 
uplifted basement block in front of Hofkirchen and Passau. The zone 
between the 575- and 625-gamma isogams is closely on the prolonga- 
tion of the fault which extends northward from Regensburg. The 
closer than normal spacing of the isogams of that zone suggests that 
the Regensburg fault extends far southward under the cover of the 
Tertiary sediments; unfortunately the survey did not cover the area 
immediately south of Regensburg; and that zone of closer than normal. 
spacing of the isogams cannot be followed in the data of the survey 
directly up to the south end of the surface exposure of the fault. 
THICKNESS OF TERTIARY SEDIMENTS 
The thickness of the prism of unconsolidated sediments from 
Ingolstadt southward across the basin to Holzkirchen can be calcu- 
lated approximately from the results of the torsion-balance survey if 
the following approximately justifiable assumptions are made: (1) 
that increase in density between the unconsolidated and consolidated 
series is concentrated at the contact between the two series; (2) that 
the base of the unconsolidated series crops out at Ingolstadt; and (3) 
that the effect from isostatic compensation of the Alps is negligible. 
The calculation can be made graphically, or by ordinary formulae: 
used in torsion-balance work. Our qualitatively quantitative calcula- 
tions from the torsion-balance data indicate that the thickness of the 
unconsolidated sediments is as follows. 
Feet Per Cent 
At Munich 8,000 +25 
Holzkirchen 13,000 +25 
Landshut 1,500 +25 
Taufkirchen 
Normally 6,000 +25 
Top of prospective structure 5,200 +25 
Rosenheim 13,000 +25 
The errors probably are all of the same algebraic sign and approxi- 
mately of the same relative magnitude. 
Geologically, the unconsolidated sediments presumably are the 
Tertiary formations, and the Mesozoic are the consolidated sedi- 
ments; but the consolidation, and consequently the density of the 
Cretaceous, may be closer to that of the Tertiary than to that of the 
Triassic and Jurassic; the Cretaceous should then be included with 
the unconsolidated sediments. 
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